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I am in the stage that I have finished my schematic and I have to select footprints for my components before heading over to PCBnew.

However, I could not find a guide on how to select footprints for my few through hole resistors and capacitors. I am very scared of this part, because this is the most important part, if your components will match the footprints.

I looked up the order I did from the website consisting of my components.

The resistors I bought fall under two categories (regarding their size.)

These two categories are:

As far as the capacitors go, there is only one type I think

NOTE: Another set of capacitors I have is this one (https://www.acdcshop.gr/capacitorceramic100nf100vy5v2024780tht5mm5524785c-p-21321.html 1). As you can see, the terminal pitch is the same. I am just adding this, because I do not know if terminal pitch is the only factor I should care about, but it is the only info provided by the page. There are no datasheets for the capacitors as you can see, unfortunately.

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  • \$\begingroup\$ Are you outsourcing the build of your boards? If yes, the vendor should have recommendations. \$\endgroup\$
    – Mattman944
    Dec 17, 2020 at 2:09

1 Answer 1

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Don't be frightened. I've been exactly where you are right now. But it's not as hard as it initially appears.

Think of what you're trying to achieve. You simply want your parts to fit through the holes and have adequate space around them. Footprint viewer is your friend:-

footprint viewer

It shows you any footprint you select via the footprint association section. It has dimensions including hole sizes if you click on them. So simply make sure that your part fits the picture dimensionally. KiCAD will automatically ensure that the components have side to side room as there is the concept of a courtyard area, which is the rectangular white outline in my screen grab.

I use a ruler or vernier gauge to measure the parts. Or you can cheat a little and look for the package type, such as DO-35 for the diode above. You'll need to decide whether to mount vertically or horizontally, and there are footprints for both.

Tip. It's best to source the parts first as that eliminates the risk that the online write up/dimensions are wrong. So for your first capacitor, I'd go with...

capacitor

= Non polarised ceramic disc capacitor, disc diameter 5mm (I guessed it), width/thickness 2.5mm (I guessed it) and of course lead pitch 5mm. If you're not designing an iPoneXIII, it will fit. See Mr. Mattman944's comment below about printing it out and test fitting first. That's really good advice.

Tip 2. See something like https://jlcpcb.com. $2 for a 100 mm x 100 mm two layer professionally made board. Unless you're looking for the whole 'I made it in my kitchen with determination, a UV torch and Sharpie' experience, there's no reason (other than speed) that anyone should make their own boards these days. China won. Just try it. What's to loose ($2 + postage)? And the experience will be worth while even if you cock it up on the first attempt. I did.

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    \$\begingroup\$ It's best to source the parts first... Yes, when I was responsible for board layouts, I would print the PWB at 1:1 and lay the actual parts on the printout. \$\endgroup\$
    – Mattman944
    Dec 17, 2020 at 15:50
  • \$\begingroup\$ @Mattman944 Yes, I should have said this :-) It builds confidence that everything fits, and that was important when I started out. On my machines, I have to set 'Crop (preserve dimensions)' in the printer dialogue so that the output scale is exactly 1:1. \$\endgroup\$
    – Paul Uszak
    Dec 17, 2020 at 17:15
  • \$\begingroup\$ "Don't be frightened. I've been exactly where you are right now. But it's not as hard as it initially appears." I just begun to read this post, up to the point i am writing this, this is the only line i have read. I must say thank you, because iyou made me feel better. I am stuck in this point for a month now (fear + procrastination hehe). I will read the rest of the post now. \$\endgroup\$ Dec 17, 2020 at 22:26
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    \$\begingroup\$ @user1584421 Those numbers are the depth, width, and pin pitch of the device. Really, pin pitch is the only one that matters very much. The dimensions of the footprints are generally included in the footprint name, when they aren't standard footprints like TO-220 or SOT-23 or something of the sort. Don't be afraid to make your own footprints either if there isn't one that fits! \$\endgroup\$
    – Hearth
    Dec 18, 2020 at 4:55
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    \$\begingroup\$ @user1584421 To answer the question for Paul, CP_Radial is for polarized (hence the P) capacitors--basically, for electrolytics. Ceramic disc capacitors get the C_Disc footprints, non-polarized cylindrical capacitors are C_Radial, and film caps are C_Rect. \$\endgroup\$
    – Hearth
    Dec 20, 2020 at 1:07

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